Physiological conditions of a patient may be monitored either during visits to a physician or through frequent self-examinations by the patient. Although the health of the patient may be determinable from these monitoring sessions, certain health issues may not be readily apparent from such periodic monitoring. Additionally, periodic monitoring through self-examination and visits to a physician can be an inconvenience to the patient.
Medical devices that are coupled to the patient either periodically or constantly, as in the case of an implant, address many of these issues. The patient is not encumbered by the manual self-examination and is not required to make frequent visits to a physician. Instead, the medical device automatically makes measurements of a physiological condition of the patient, such as pulse or respiration rate, and stores the information for later retrieval or streams the data to another device or communication network. Thus, the physiological condition of the patient can be automatically monitored at anytime during which the medical device is coupled to the patient, regardless of context.
However, context may temporarily affect the physiological condition of the patient being monitored. Context can be divided into both a patient context and an environmental context. The patient context is a body-related factor, such as the posture, activity level, or mental/emotional state of the patient, and the patient context can cause the physiological condition of the patient to vary to a substantial degree. The environmental context is an external factor such as the ambient temperature or sound level and can also cause the physiological condition to vary.
The context is typically unknown when the medical device is making the physiological measurements, and therefore any deviations from normal values for a physiological condition may be the result of context rather than a health condition of the patient. Therefore, the physiological measurements being made regardless of context cannot be relied upon with a high degree of certainty when assessing the health of the patient since the unknown context may skew the measurements.
Additionally, the context may be relevant to the type of therapy that is being provided to a patient. For example, for certain contexts the patient may be better served by a particular mode of therapy from a medical device, such as immediate defibrillator shocks while driving upon detection of fibrillation. For other contexts, the patient may be better served by a different mode of therapy from the medical device, such as taking more time to more accurately determine the patient's condition before administering defibrillator shocks. However, because the context is typically unknown, the medical device administers the defibrillator shocks without regard for the context surrounding the patient at any given time.